Devices for automatically ascertaining capacitance, dissipation factor and insulation resistance of a plurality of capacitors to be tested are generally known, for example, see U.S. Pat. No. 4,931,721. A known rotary capacitor electrical test system includes an instrument that provides the voltage source to a capacitor under electrical test. The instrument contains two groups of four different types of circuit boards that plug vertically into a card cage. The boards can be inserted and removed independently. These boards work together to provide the voltage source, current source, and output voltage measurement capability. The circuitry is split into four separate circuit boards because it is not feasible to fit all of this circuitry into the available form factor. When assembling a system for the first time, in-circuit verification can take place on the individual circuit boards, and a test fixture can be made to test each board. However, the group of boards cannot be tested together until they are all installed in the system, and a system test procedure is run. When there is a failure in this group of boards, it is not immediately apparent which board in the group has failed. Therefore, all four boards must be checked for problems.
When boards do fail, it is not known how long the board has been in operation, what its output conditions were, and what temperatures the board has been subjected to. This data would be useful in determining the lifetime of the circuitry and understanding the failure modes and vulnerabilities.
Some failures might be able to be prevented if it were possible to monitor sensitive circuitry and shut it down or flag an error when certain limits are reached. Without onboard intelligence, this is more difficult to do.
Another problem is warranty tracking of these circuit boards. If a customer takes a board from a spare system to get a failed system running again, this is a violation of warranty policy. However, there is no way to track this event aside from a handwritten serial number written on the Printed Circuit Board (PCB).
Individual boards can be tested separately in many different ways to ensure they were built properly. However, they eventually need to be plugged into a system to verify that they are working with each other, so an in-system test must be run. If a failure is detected, it must be diagnosed in-system.
Existing electrical capacitor test instruments do not use a modular approach. Limited internal read back capability is present in the existing systems, so a number of external meters must be used to troubleshoot and calibrate the boards in-system. Serialization is handled with handwritten numbers on the PCB, and is not known to the hardware.